Power conversion through DC to AC inverters has conventionally been achieved without concern for having the inverter itself match itself with the load, which is conventionally inductive. A mismatch affects the power factor and hence efficiency of power conversion and consequently more input power is drawn than is in fact needed. In practice, therefore, where there is only a limited supply of input power and/or where conversion efficiency should be optimized, less than efficient conversion will result.
While it has been appreciated that input power should be minimized and the power conversion system rendered more efficient by means of load matching, no means nor method for effecting this in any suitable manner has been provided within inverters. Load matching has been effected by selecting a number of capacitors external to the inverter and experimenting in tuning the circuit for power reduction. This requires the installer physically to connect and disconnect different capacitors until the best possible tuning is achieved. In practice this laborious task is invariably ignored or is dangerous because of the parameters of the inverter, the load and the environment of the circuitry.
In the publication Flite-Tronics published Nov. 1, 1977, on page 206, there is shown circuitry wherein a bank of capacitors is connected in parallel across the secondary winding of a transformer. These capacitors, however, do not serve the purpose of load matching but rather convert the square wave output existent across the secondary of the transformer into a sine wave, the initial transformation across the transformer of a square wave providing more efficient power transformation than if a sine wave were fed to the transformer primary. This common practice is known as "Brute Force Wave Shaping." Devices of this nature use a large capacitor merely for wave shaping.